Dust-control mats, typically used in or near entrances in retail and industrial buildings, offices, and residences, can be classified into two types, according to their essential construction: a unitary mat and a separable mat. Mats of both types are commonly used in industrial laundry businesses that rent the mats to customers for a period of time and then recover, wash, regenerate and re-rent the mat, to the same or to a different customer.
In the case of unitary mats, the base or floor portion and the textile mat portion are constructed as a unitary, inseparable structure. When such mats are used In the industrial laundry business, both portions of the mat—including the base portion (typically made of a relatively thick layer of rubber or similar material)—must be recovered, transported to and from the customer location, washed and regenerated, even though it is likely that only the textile portion requires laundering. Having to include the relatively heavy base or floor portion of the mat in these various operations causes significant and needless inefficiencies due to the additional weight and bulk contributed by the base or floor portion, including the considerable energy costs associated with transporting and washing such mats.
In order to reduce these inefficiencies, and to provide additional flexibility and variety in the choice of the textile portion of the mat, separable mats have been developed. These mats typically are comprised of a base portion and a separate, removable textile portion that is adapted for fitting in or on the base portion. The heavier, bulkier base portion can then remain in place, while the lighter, less bulky textile portion can be removed or exchanged for laundering or, for example, for the purpose of changing the appearance of the mat as an interior design element in a customer's building. Because only the relatively lightweight, compact textile portion need be serviced, industrial launderers can achieve significant economies during the collecting, laundering, and re-distributing processes that such laundries routinely undertake during the lifetime of the textile portion of the mat, and substantial cost savings can be realized if the relatively heavy and bulky base portion can be left in place.
The concept on which such separable mats are based is that the base portion, being made of rubber or the like, can remain in place on a semi-permanent basis once it is placed in the desired location. Thereafter, the textile portion of the mat can be replaced or exchanged as housekeeping or interior design needs arise. Accordingly, in addition to a reduction in the inefficiencies referred to above, an interchangeable system of mats can be produced to meet a variety of user needs and specifications, making it possible to offer a wide variety of mats at relatively modest cost, and allowing for easy replacement or substitution of the textile portion of the mat.
The separable mat, however, requires some mechanism to provide secure and reliable attachment between the base portion and the textile portion. If such mechanism is ineffective, the textile portion of the separable mat can exhibit turned-up edges, ripples, and/or mis-alignment with the base portion, all of which can result in conditions that are both unsightly (due to mat misalignment, curling, or the like) and unsafe (due to the tripping hazard presented by such turned-up edges, ripples, or other surface irregularities). Additionally, such mats provide impaired ability to remove soil, moisture, or debris from shoes, thereby adversely affecting the essential functionality of the mat.
In order to assure adequate and dependable attachment between the base portion and the textile portion of such mats, and thereby eliminate unsightliness as well as a principal cause of tripping, several methods for detachably securing the base portion to the textile portion have been developed. These methods include, among others, (1) use of a face fastener; (2) use of combination of rough surfaces; (3) use of a mechanical fastening device; (4) use of a chemical adhesion agent; and (5) use of a magnetic material.
One physical and partial adhesion mechanism based upon a hook-and-loop fastener has generally been used as disclosed in, for example, Japanese Patent Publication No. 7450/1984. Described in detail, a female loop portion of the fastener is installed on the back surface of the textile portion of the mat, while a male hook portion of the fastener is installed on the upper surface of the base. Typically, when used with mats that are generally square or rectangular in shape, such fasteners are installed in the corners and along the sides of the mat. However, such placement is unable to avoid wrinkling, which can develop when non-adhered portions of the sides are contacted by the foot traffic. Such wrinkling, and the resulting tripping hazard it presents, can have a dramatic, adverse effect on the safety and appearance of the mat. When the face fastener is used along the entire side of the mat, or substantially so, the mat may become undulated after repetitive washing due to a difference in the shrinkage between the mat fabric and the fastener portion. Regardless of the positioning of the fastener, such fasteners tend to add undesirable thickness and bulk to the mat, thereby causing lumps, depressions, or other surface irregularities in the mat and, where the mat is used near a door with minimal floor clearance, interference with the smooth operation of the door. It has also been observed that such fasteners tend to lose their binding effectiveness, i.e., their adhesion strength, with repeated launderings. In addition, from the standpoint of manufacturing steps, the face fastener must be stitched after the fabric is prepared, thereby increasing the manufacturing cost.
In the case of an attachment mechanism using rough surfaces or a mechanical fastening device, a shape must be formed on the back surface of the fabric that inevitably results in an increase in cost and weight. Moreover, such mechanisms are associated with other shortcomings: an effective adhesive force is difficult to obtain in the vertical direction, the roughened portions themselves become worn out through repetitive laundering of the fabric, and the fabric on the surface tends to deteriorate (wear out), causing the life of the mat to be shortened.
In the case of an attachment mechanism using a releasable adhesive material, the adhesive force decreases upon the infiltration of rain, sand and the like, making it difficult to maintain reliable and effective attachment between the mat portions under all weather conditions.
In contrast with the above-mentioned adhesion methods, the adhesion using magnetic materials maintains an adhesive force favorably and stably against changes in an external environment and varies little even after repeated laundering.
Several attachment mechanisms using magnetic materials already have been proposed for the purpose of releaseably securing together the portions of a separable mat. Such mechanisms are described in, for example, Japanese Laid-Open Patent Publication No. 28413/79, Japanese Laid-Open Utility Model Publication No. 16976/1984, Japanese Laid-Open Utility Model Publication No. 95079/1985 and Japanese Laid-Open Patent Publication No. 118774/1985, and European Patent Specification EP 0653179 B1.
As used herein, the term “magnetically active” shall be used to refer to a material that is or that forms a magnet, i.e., it generates a magnetic field. The term “magnetically passive” shall be used to refer to a material that is attracted to a magnet but that cannot, of itself, generate a magnetic field. The term “magnetically interactive” shall refer to a material that is either magnetically active or magnetically passive. The term “magnetically complementary” shall be used to describe magnetically interactive materials that, when brought into close physical proximity, generate or establish an attractive force between the materials. Pairs of magnetically complementary materials include a magnet and a ferrous material (e.g., iron) or, alternatively, a first magnet and a second magnet having a pole orientation that causes it to be attracted to the first magnet.
When using magnetic forces to releasably attach separable mat components, it is important that the textile or removable portion be securely fastened to the base or floor portion. To achieve this result, it is generally understood that the adhesion surface preferably should be smooth and the gap between the opposing magnetically interactive materials in the respective mat portions preferably should be as small as possible, so as to maximize the strength of the attractive forces generated by the magnet(s). In the case of a mat on which pile yarns are implanted, however, it is difficult to completely avoid the unevenness caused by the stitching of pile yarns on the primary backing layer associated with the back surface of the fabric. When an ordinary magnetic material is used, therefore, it is in many cases difficult to establish a sufficiently strong and uniform attachment.
The above-mentioned problem can be solved to some extent by using magnetically active materials that generate a strong magnetic force. In rental mats, however, it is difficult to employ a magnetic material having a particularly strong magnetic force from the standpoint of cost and weight. In addition, when the mat is adhered using a magnetically active material having a particularly strong magnetic force, it becomes difficult to maintain uniformity of adhesion. Moreover, once the mat becomes wrinkled, the strong magnetic forces then tend to oppose any subsequent smoothing action intended to remove the wrinkles.
Because of such circumstances, magnetic force has not yet been practically utilized for fixing the mat to the base though many proposals have been made regarding the use of magnetic force.